The present disclosure is related with the detecting method of the abnormalities by the instantaneous power failure of a hard disk.
Following shows typical examples as technology for solving a problem that happens in a hard disk in an instantaneous power failure.
First, in one example, if reduction of an AC input voltage provided to a printer is detected, it will be notified to a controller part and an access operation to the hard disk drive will be stopped.
In another example, a control unit resets a state of the disk interface part by interruption at the time of AC power off. Further, the disk controller of an external storage identifies the reset state of an interface and writes data of one access unit under writing to a hard disk with adding error check code within DC voltage guarantee time.
Also, in the other example, when a digital value of output voltage is less than a desired value, it is determined that AC power supply is intercepted, an input DC voltage of a converter declines, and output voltage will lower soon. In this case, new data to nonvolatile memory is not written in.
Also, in the other example, when a digital value of momentary voltage of an alternating voltage source is greater than or equal to a predetermined threshold, it outputs. In this case, if the period from falling to rising exceeds a first time limit value for this output wave, it determines as the instantaneous power failure. Thereby, main work is interrupted.